Vibration-sensitive electric switch

ABSTRACT

A vibration-sensitive electric switch, for use in percussion or vibration fuses, particularly for hand and rifle grenades, as well as mines, having a pair of contacts, one of which is supported for movement into contact with the other contact in response to application of forces thereto and at least one of said contacts being deformable at least in the area of contact with said other contact so as to increase the contact time therebetween.

United States Patent Gawlick et al.

[ Apr. 18, 1972 [54] VIBRATION-SENSITIVE ELECTRIC SWITCH [72] Inventors: Heinz Bendler, Nurnberg; Gunter Kalchreuth, all of Germany [73] Assignee: Dynamit Nobel AG, Troisdorf, Germany [22] Filed; Jan. 27, 1970 [21] AppLNo: 6,219

(iawlick, Furth, Bay; lieilmut Hubsch,

[30] Foreign Application Priority Data Feb. 4, 1969 Germany ..P 19 05 295.0

[52] US. Cl. ZOO/61.45 R, 102/702, ZOO/166C [51] 1nt.Cl. ..H01h35/14 [58] Field ofSearch ..200/6l.45,61.53,166C,61.49;

[ 56] References Cited UNITED STATES PATENTS 2,662,945 12/1953 Cockram ..200/61.49

3,465,109 9/1969 Williams ..200/61.04 3,337,701 8/1967 Prebilic... ZOO/61.45 2,763,773 9/1956 Morente. ..200/61.52 3,052,784 9/1962 Ousley 102/702 X 3,416,451 12/1968 Hamerla ..102/70.2 3,369,097 2/1968 Murakami .200/166 C 3,415,960 12/1968 Kollmeyer ..200/61.49

Primary Examiner-Robert K. Schaefer Assistant Examiner-M. Ginsburg Attorney-Craig, Antonelli & Hill [57] ABSTRACT A vibration-sensitive electric switch, for use in percussion or vibration fuses, particularly for hand and rifle grenades, as well as mines, having a pair of contacts, one of which is supported for movement into contact with the other contact in response to application of forces thereto and at least one of said contacts being deformable at least in the area of contact with said other contact so as to increase the contact time therebetween.

14 Claims, 2 Drawing Figures PATENTEDAPR 1 8 I972 FIGI FIG 2 INVENTORS HEINZ GAWUCK HE M TBEN ,R GU R HU i ,zinxlnw, 422M041 v M ATTORNEYS VIBRATION-SENSITIVE ELECTRIC SWITCH This invention relates to a vibration-sensitive electric switch having a housing and two contacts arranged in this housing, one of which contacts is movably disposed in the housing and comes into contact, upon vibration, with the other contact which is fixedly connected with the housing.

Such electric switches serve the purpose of triggering, when acceleration forces or deceleration forces of a certain magnitude are exceeded, actions of a great variety of devices which may be connected to such switches. Thus, they can be utilized, for example, to actuate special safety devices in automotive vehicles hitting a fixed obstacle, or to trigger signaling or measuring units in case of vibrations. As is conventional, such switches can, moreover, also be employed advantageously in percussion or vibration fuses, particularly for hand grenades and rifle grenades, as well as mines.

The sensitivity of response of these switches increases with a decrease in the mass of the movable contact and a reduction in the forces exerted on the movable contact by the member effecting the holding thereof, for example a coil spring. However, this means that minimum holding forces and therefore also minimum restoring forces due to the mounting must not fall below a certain limit, in order to safely avoid too great a sensitivity and thus any unintended response at even very small accelerative forces. Although the response limit of this switch could also be increased by increasing the movable contact mass, such measure is generally impractical because of the requirement for as small a structural size as possible, or as low a weight for the switch as possible.

Since the duration of the contact between the two contacts, which are conventionally manufactured, for example, of copper or steel, depends on the size of the restoring forces acting in total on the movable contact, a lower sensitivity of response entails also a larger restoring force, in view of the larger holding force required for this purpose, and thus also results in a shorter duration of contact between the colliding contacts. In order to obtain a sufficiently reliable functioning of the units connected to the switch even in such a case, these units must accordingly be designed to be highly sensitive so that they respond even in case of an electric current of a shorter duration. Such highly sensitive devices, for example electric primers in detonators, however, in addition to being more susceptible to disturbances and more expensive, exhibit in certain circumstances also the disadvantage of providing diminished safety in handling.

The invention is based on the problem of avoiding the above-described disadvantage, i.e., of lengthening, at the same sensitivity of response, the duration of contact between the contacts to such an extent that it becomes possible to employ devices connected to the switch which exhibit also a lower sensitivity.

This problem is solved, in accordance with the invention, by making at least one of the two contacts, at least in the area of common contact, of a readily plastically and/or elastically deformable, electrically conductive material. This has the result that the force, which drives the movable contact backward after the collision with the contact fixedly arranged in the housing, and which is superimposed on the restoring force due to the mounting, is lessened, or the generation thereof is delayed in time; this delay is larger, the higher the proportion of kinetic energy which is converted into heat during the percussion process by plastic or elastic deformation, or which is stored for a longer or shorter period in the elastically deformed material.

It is a principle object of the present invention to provide a vibration sensitive electric switch which eliminates or otherwise avoids the disadvantages and objectionable features inherent in known devices.

It is another object of the present invention to provide a vibration sensitive electric switch which is characterized by an increased duration of contact between contacts while maintaining a high sensitivity.

It is a further object of the present invention to provide a vibration-sensitive electric switch which is capable of use with devices which exhibit a lower sensitivity by providing an increased time of actuation of the switch.

It is still a further object of the present invention to provide a vibration sensitive electric switch wherein an increased time of actuation is achieved by relatively simple and inexpensive means.

These and other objects, features and advantages of the present invention will become more apparent from the following detailed description thereof, when taken in conjunction with the accompanying drawings, which illustrate one exemplary embodiment for use in a percussion or vibration fuse or primer, and wherein:

FIG. 1 is a partial sectional view of a switch according to the present invention in the inoperative position; and

FIG. 2 is a partial sectional view of the switch of FIG. 1 in the armed or operative position.

According to FIG. 1, the contact 2, fixedly disposed in the electrically conductive housing 1, is electrically insulated from the housing 1 by means of the insulation 3. The other contact 4, designed as a vibrating contact, is connected by means of the coil spring 5 electrically and mechanically with one pole of the battery 7, the other pole of which is in electrically conductive connection with the housing 1 in the well-known manner. The coil spring 5 is held at the contact 4 and at the pole of battery 7, respectively, by means of individual extension members 8, formed at the contact 4 and at the pole of the battery 7', the extension members 8 are optionally additionally provided with an appropriate thread for safer connection with the coil spring 5 and the contacting surfaces thereof are rounded or contoured to permit free pivoting of the member connected to the contact 4 with respect to the member connected to the pole of the battery, as will be described in connection with FIG. 2.

The battery 7 is at zero voltage in the safe position and is activated only in the armed position by means of potassium hydroxide solution fed from a separate container, which latter is not shown. In order to take into account the possibility that, under certain circumstances, potassium hydroxide solution passes unintentionally into the battery even in the safe position, the poles of this battery 7 are short-circuited by means of the electrically conductive ring 9, which ring connects the contact 4 with the housing I and simultaneously also holds the contact 4 at a spacing from contact 2.

The contact 2 is provided, on the side facing the contact 4, with an axial extension 10, which latter is made, for example, of tin and has the shape of a pin; this extension can be manufactured integrally with the contact 2, or also separately therefrom, and in the latter case can also be made of a different material. If the last-mentioned mode is employed, care must only be taken that both components can be connected with each other sufficiently firmly, so that a flawless electrical connection is ensured even under the shock effect produced during contact with the other contact 4. The contact 4, on the side facing the extension 10, is provided with an axial recess 1 I To achieve the armed position of the switch shown in FIG. 2, the battery 7 is moved, under an appropriate pressure, in the direction toward the contact 2 up to the stop 12 so that, due to the fact that the extensions 8 test against each other in the safe position, the contact 4 is pushed through the ring 9 and thus is made freely movable. The individual components of the switch are positioned with respect to one another in such a manner that the extension 10 of the contact 2, in the rest position of contact 4, extends into the recess 11 thereof without touching the contact. Simultaneously with being axially advanced, the battery 7 is activated by solution of potassium hydroxide fed thereto, so that now a difference in electric potential of a corresponding magnitude is created between the housing 1 and the contact 4.

The pressure, indicated by the arrow A, to actuate the switch is produced, for example, by means of a primer charge,

not shown, burning with the evolution of gas, which primer charge is itself ignited by a delay charge, likewise not shown. The delay period is dimensioned, in this connection, such that at least the vibrations which are unavoidable during the ignition of the delay charge do not influence the switch in its armed position.

If, in the armed position, an impact of sufficient size impinges on the housing 1, the contact 4 is deflected from its rest position, as indicated in dashed lines, and touches the extension of contact 2 during a time interval determined in ac cordance with the selected materials, the shape of the contacts, and the coil spring 5. Thus, the circuit is closed by way of a bridge primer, not shown, the two poles of which are connected to the housing 1 and the contact 2, so that the charge, likewise not shown, connected to the bridge primer, is ignited.

As already indicated, in order to increase the duration of contact between the contacts 2 and 4, contact is effected via the extension 10, which may be formed of a readily plastically and/or elastically deformable, electrically conductive material. This prevents or at least substantially reduces the.very sharp rebound produced between extremely hard, nondeformable objects which tends to provide a very short contact time therebetween. As is apparent, the desired delayed return of the movable contact to its non-contacting position can be accomplished in accordance with the present invention by properly selecting the material for the contacting extension 10 or the contact 4, and/or providing the extension 10 of the proper size and shape to provide for a deformation of material upon contact between the respective contacting elements.

Thus, it is possible, by the selection of a suitable material, to vary the duration of contact between the contacts within relatively wide limits, with the sensitivity of response remaining the same. For example, aluminum or also electrically conductive plastics with suitable mechanical properties can be employed for this purpose. In view of the fact that the function of the electric switch is, however, the more satisfactory the higher the electrical conductivity of the contacts and the lower the contact resistance between these contacts, the suggestion is advanced, in a suitable embodiment of the invention, to employ, as the readily plastically and/or elastically deformable, electrically conductive material, tin, optionally with an addition of antimony, silver, or gold. in this connection, the addition of antimony, about l-3 percent by weight, serves in a conventional manner for maintaining the electrical conductivity of the tin, by suppressing or at least substantially reducing the surface oxidation of the tin which occurs over longer periods of time without the addition of antimony.

For the purpose of lowering the costs for the material, the provision is made, according to another suggestion of this invention, to apply the readily plastically and/or elastically deformable, electrically conductive material to another carrier material having suitable mechanical properties. Since, in this connection, no requirements whatsoever need be met by the carrier material from an electrical viewpoint, which requirements must rather be fulfilled merely by the applied thin layer of, for example, silver or gold, the selection of a carrier material satisfying the respective necessities can be made extensively as desired. Thus it is possible, for example, to employ for this purpose lead, or also any electrically non-conductive synthetic material. as long as the latter only satisfies the demand of being readily deformable. The electrically conduc tive layer can be intimately bonded to the carrier material, which is possible without difficulties, for example, when using a metallizable plastic; however, it is also possible for the layer to merely contact the surfaces of the carrier material more or less firmly.

The above-explained conversion of the kinetic energy of the movable contact into deformation work is further promoted by the fashioning, in accordance with the invention, of the contact 2 which is fixedly connected to the housing with the axial extension 10 of readily plastically and/or elastically deformable, electrically conductive material, which extension projects, in the rest position of the other contact 4, which latter is constructed as a vibrating contact, without touching into the recess 11 provided in the latter contact, so that the deformation of the colliding contacts is also enhanced by the external shapes thereof.

In view of the fact that it is preferred, in detonatable systems with electric ignition, for safety reasons, to employ bridge primers, for example, exhibiting an incandescent wire, instead of highly sensitive primer elements, the flawless functioning of which bridge primers is only ensured at a minimum contact time of the contacts of about 3 milliseconds, the switch of this invention is preferably employed in percussion or vibration fuses, particularly for hand and rifle grenades, as well as mines.

Although the present invention has been described with reference to but a single embodiment, it is to be understood that the scope of the invention is not limited to the specific details thereof, but is susceptible of numerous changes and modifications as would be apparent to one with normal skill in the pertinent technology.

What we claim is:

l. A vibration-sensitive electric switch comprising first and second electrical contacts, and support means for supporting said first contact for vibrational movement into contact with said second contact in response to forces applied thereto; at least one of said first and second contacts being readily plastically deformable to provide permanent deformation in the area of contact with said other contact so as to increase the contact time therebetween.

2. A vibration-sensitive electric switch as defined in claim I, wherein at least said area of contact on said one of said first and second contacts is formed of electrically conductive material.

3. A vibration-sensitive electric switch as defined in claim 1, wherein at least said area of contact on said one of said first and second contacts is fonned of a readily plastically deformable, electrically conductive material.

4. A vibration-sensitive electric switch as defined in claim I, wherein at least said area of contact on said one of said first and second contacts is formed of a metal selected from the group consisting of gold, silver, tin, and tin with the addition of antimony thereto.

5. A vibration-sensitive electric switch as defined in claim 1, wherein said one of said first and second contacts is formed of a base part having a readily plastically deformable, electrically conductive material provided as a coating over at least a part thereof forming said area of contact.

6, A vibration-sensitive electric switch as defined in claim 5, wherein said base part is formed of an electrically non-conductive, deformable material.

7. A vibration-sensitive electric switch as defined in claim 1, wherein said support means includes a housing fixedly supporting said second contact and means including a spring connected to said first contact for supporting said first contact for vibrational movement in the vicinity of said second contact.

8. A vibration-sensitive electric switch as defined in claim 7, wherein said housing includes a support ring for supporting said first contact in an inoperable fixed position and said means for supporting said first contact for vibrational movement includes means for disengaging said first contact from said support ring for arming the switch.

9. A vibration-sensitive electric switch as defined in claim I, wherein said first contact is provided in the form of a cup having an internal space and said second contact includes an axial extension projecting into said internal space.

it]. A vibration-sensitive electric switch as defined in claim 9, wherein said axial extension is formed of a readily plastically deformable, electrically conductive material.

11. A vibration-sensitive electric switch as defined in claim 9, wherein said axial extension is fonned of a metal selected from the group consisting of gold, silver, tin, and tin with the addition of antimony thereto.

12. A vibration-sensitive electric switch as defined in claim 9, wherein said axial extension is formed of a non-conductive tact and supporting said contact for movement in response to forces applied to said housing.

14. A vibration-sensitive electric switch as defined in claim 13, wherein said battery is slideable in said housing between first and second positions, a conductive support ring secured to said housing and contacting said first contact only in the first position of said battery, said first contact being translatable with movement of said battery to said second position to a position wherein contact with said second contact is possible. 

1. A vibration-sensitive electric switch comprising first and second electrical contacts, and support means for supporting said first contact for vibrational movement into contact with said second contact in response to forces applied thereto; at least one of said first and second contacts being readily plastically deformable to provide permanent deformation in the area of contact with said other contact so as to increase the contact time therebetween.
 2. A vibration-sensitive electric switch as defined in claim 1, wherein at least said area of contact on said one of said first and second contacts is formed of electrically conductive material.
 3. A vibration-sensitive electric switch as defined in claim 1, wherein at least said area of contact on said one of said first and second contacts is formed of a readily plastically deformable, electrically conductive material.
 4. A vibration-sensitive electric switch as defined in claim 1, wherein at least said area of contact on said one of said first and second contacts is formed of a metal selected from the group consisting of gold, silver, tin, and tin with the addition of antimony thereto.
 5. A vibration-sensitive electric switch as defined in claim 1, wherein said one of said first and second contacts is formed of a base part having a readily plastically deformable, electrically conductive material provided as a coating over at least a part thereof forming said area of contact.
 6. A vibration-sensitive electric switch as defined in claim 5, wherein said base part is formed of an electrically non-conductive, deformable material.
 7. A vibration-sensitive electric switch as defined in claim 1, wherein said support means includes a housing fixedly supporting said second contact and means including a spring connected to said first contact for supporting said first contact for vibrational movement in the vicinity of said second contact.
 8. A vibration-sensitive electric switch as defined in claim 7, wherein said housing includes a support ring for supporting said first contact in an inoperable fixed position and said means for supporting said first contact for vibrational movement includes means for disengaging said first contact from said support ring for arming the switch.
 9. A vibration-sensitive electric switch as defined in claim 1, wherein said first contact is provided in the form of a cup having an internal space and said second contact includes an axial extension projecting into said internal space.
 10. A vibration-sensitive electric switch as defined in claim 9, wherein said axial extension is formed of a readily plastically deformable, electrically conductive material.
 11. A vibration-sensitive electric switch as defined in claim 9, wherein said axial extension is formed of a metal selected from the group consisting of gold, silver, tin, and tin with the addition of antimony thereto.
 12. A vibration-sensitive electric switch as defined in claim 9, wherein said axial extension is formed of a non-conductive base part having a readily plastically deformable, electrically conductive layer thereon.
 13. A vibration-sensitive electric switch as defined in claim 9, for use in percussion or vibration fuses, particularly for hand and rifle grenades, as well as mines, wherein said support means includes a housing, said second electrical contact being fixedly supported in electrically insulating relationship at one end of said housing, a battery supported in said housing having one pole thereof in contact with said housing, and a spring interconnecting the other pole of said battery and said first contact and supporting said contact for movement in response to forces applied to said housing.
 14. A vibration-sensitive electric switch as defined in claim 13, wherein said battery is slideable in said housing between first and second positions, a conductive support ring secured to said housing and contacting said first contact only in the first position of said battery, said first contact being translatable with movement of said battery to said second position to a position wherein contact with said second contact is possible. 